Abstract This K01 Mentored Research Scientist Development Award will provide the candidate, Jaime Booth, PhD., with advanced training and structured mentoring to facilitate her transition to research independence. The candidate?s goal is to become an independent investigator with expertise in neighborhood processes that may be modified to prevent substance use among low-income adolescents. The proposed scope of work will fill a marked gap in existing literature by examining the role of neighborhood process on tobacco and marijuana use (TMU) from a social stress perspective. While TMU among adolescents is declining nationally, use among samples of low-income adolescents remains high. The lack of decline of TMU within this population may be partially attributed to the higher rates of stress experienced by low-income adolescents. One key source of stress is neighborhood disadvantage. Despite some evidence that neighborhood stressors impact adolescent stress and subsequent TMU, findings have been inconsistent, potentially in part due to methodological challenges, such as the use of cross-sectional data and census tracts to define neighborhood risk. To gain substantive expertise in assessing neighborhood processes germane to adolescent development and methodological expertise in advanced quantitative methods that will allow the candidate to addresses these challenges, the candidate will pursue training in This award will provide training and mentorship in: 1) the role of stress in adolescent TMU, 2) knowledge about and measurement of parental monitoring during adolescence as both a mediator and a potential moderator between neighborhood-related stress and TMU, 3) cross-lagged and multilevel modeling with longitudinal data, and 4) the use of EMA to understand adolescents' exposure to neighborhood stress in real time. This training will be achieved by conducting two research studies that address the following aims: 1) Examine the potential mediating/moderating role of parental monitoring in the association between neighborhood disadvantage and adolescents' stress and TMU; and 2) Understand the relation between adolescents? exposure to activity spaces, and social networks and TMU via adolescents' perceptions of neighborhood risk and protection and stress. This K01 award will provide the candidate with protected time to develop expertise in the role of neighborhood stress in adolescent TMU and the use of GSP and EMA to understand complex stress processes. By the conclusion of the award, this training and research experience will position the candidate as one of the few researchers in the U.S. with the necessary skills to design intensive longitudinal studies for investigating factors within disadvantaged neighborhoods that may place adolescents at risk for substance use. Furthermore, the K01 will provide the candidate with the requisite knowledge to identify modifiable targets of intervention within neighborhoods and more precisely test the effects of neighborhood change on TMU in adolescents.